The newly-unveiled Kindle Fire HD line of tablets by Amazon has definitely upped the online retailer's game in the color tablet arena; but, going by the results of some early tests, the devices are not necessarily the best color tablets around.

With the key advantages of the new 7-inch and 8.9-inch Kindle Fire HD tablets - which will ship on September 14 and November 20 respectively - being low price-tags for the base models and easy access to Amazon's content offerings, Amazon has been asserting that the tablets are best seen as front doors to its online stores.

However, going by some early tests of the Kindle Fire HD tablets, it has been found that, so far as the 7-inch model - which costs $199 for the base model - is concerned, the tablet is neither is it as polished as the Apple iPad, nor is it fluid or versatile.

In fact, one of the most irksome aspects of Amazon's new Kindle Fire HD line is that users are virtually battered with ads which occupy the complete screen each time they start or resume the use of the tablets. Though users can go to an obscure setting on a Web page to `opt out' of the ads, they have to make an additional payment of $15 for it.

Moreover, the Kindle fire HD tablets also notably lack some of the features offered in the costlier iPad; including a back camera, built-in dictation functionality, instant messaging and maps, and artificial-intelligence features like Siri.